High amperage fault currents have been known to occur in electrical power systems. Therefore, it has been the practice to incorporate in such systems protective apparatus capable of interrupting the circuit safely under such high amperage fault current conditions. Other control apparatus incorporated in such systems, such as switches or contactors, normally have not been capable of opening power circuits safely under overload or high fault current conditions, this being left to such protective apparatus designed for that purpose. To avoid destructive damage to such contactors, or switches, it has been the practice to provide special means for maintaining their contacts closed and to prevent their contacts from being blown open under high fault current conditions until the aforementioned protective apparatus has had time to operate to interrupt the circuit. Such special means for keeping the contacts closed under high fault current conditions have taken the forms of a larger operating magnet, mechanical latching means or the like. However, such approach has had the disadvantages of increasing the size of the magnet or requiring added latch components resulting in an increase in the size and cost of a contactor or switch. This invention relates to improvements thereover.